
def main():
  x = int(input())
  if x >= 30:
    print('Yes')
  else:
    print('No')
  
  
main() def main():
  x = int(input())
  if x >= 30:
    print('Yes')
  else:
    print('No')
  
   main x = int(input()) x int(input()) int input() input if x >= 30:
    print('Yes')
  else:
    print('No')
  
   x >= 30 x 30 print('Yes') print 'Yes' print('No') print 'No' main() main def main():
  x = int(input())
  if x >= 30:
    print('Yes')
  else:
    print('No')
  
   def main():
  x = int(input())
  if x >= 30:
    print('Yes')
  else:
    print('No')
  
   main

def main():
  x = int(input())
  if x >= 30:
    print('Yes')
  else:
    print('No')
  
  
main()